Family : Orchidaceae
Text © Pietro Puccio
English translation by Mario Beltramini
The species is native to Assam, Laos, Thailand and Vietnam where it lives in the evergreen forests between the 500 and the 1400 m of altitude.
The name of the genus is the combination of the Greek substantives “δένδρον” (dendron) = tree and “βίος” (bios) = life, with reference to the numerous species of the genus living on the trees; the specific name takes the name of its collector, Rita.
Common names: Thạch hộc,Tam Đảo (Vietnam).
The Dendrobium ritaeanum King & Pantl. (1897) is an epiphyte species with thin, ramified stems, and cylindrical to fusiform pseudobulbs, 3-4 cm long and of 0,5-0,7 cm of diameter, with at the apex one single oblong-lanceolate leaf with sub-acute apex, 5,5-10 cm long and 12-1,6 cm broad.
Apical inflorescence bearing 1-2 sub-sessile flowers, of 1,2-1,6 cm of diameter, of pale yellow colour.
Dorsal ovate-lanceolate sepal with sub-acute apex, about 7 mm long and 3 mm broad, lateral ovate-triangular sepals, sickle-shaped, sub-acute, about 8 mm long and 5 mm broad, merged at the base to form a sort of conical, obtuse, about 8 mm long spur (mentum).
Oblong-linear petals with obtuse apex, 6-7 mm long and 2 mm broad, trilobate labellum, 1,2-1,5 cm long and 0,6-0,7 cm broad, with short lateral lobes, obtuse, erect, and median lobe with apex divided in two elliptic lobes run at the centre by two crests of purple colour.
It reproduces by seed, in vitro, and by division, with each section provided of at least 3-4 pseudobulbs.
Species rare in cultivation, present almost exclusively in specialized collections, requires a semi-shady position, intermediate temperatures, high humidity and air in constant movement. It can be mounted on pieces of bark or cork rafts or cultivated in pot with draining and aerated compound that may be formed by fragments of bark and charcoal with addition of inerts to improve the drainage. The watering must be regular during the growth of the pseudobulbs, but allowing to dry up before giving water again, more spaced in winter until the beginning of the blooming, utilizing rain water, demineralized or by reverse osmosis.
Divisions, transplants and repottings are to be done when the new roots appear signalling the vegetative regrowth.
The species is inscribed in the appendix II of the CITES (species whose trade is internationally ruled).
Synonyms: Desmotrichum ritaeanum (King & Pantl.) Kraenzl. (1910); Ephemerantha ritaeana (King & Pantl.) P.F.Hunt & Summerh. (1961); Flickingeria ritaeana (King & Pantl.) A.D.Hawkes (1961).
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